During the manufacture and forming of many products from plastic, significant amounts of plastic waste material are frequently produced. Applicant has previously invented several unique apparatus for comminuting waste material, particularly plastic sheet material, into small, rather uniform particles or pieces that can be readily recycled or disposed of in an environmentally acceptable manner. Several generations of product line have been sold by Applicant under the product name "Chesaw" and have gained commercial success. One such prior invention is the subject of the Irwin, et al, U.S. Pat. No. 4,687,144 granted Aug. 18, 1987 and assigned to Irwin Research and Development, Inc. Another such prior invention directed to an improved device is the subject of Patent Cooperation Treaty (PCT) International Application PCT/US94/06412 published on Dec. 14, 1995, having International Publication No. WO 95/33566, and listing as Applicants (for all designated states except U.S.) Irwin Research and Development, Inc. Yet another such prior invention directed to an improved device is the subject of U.S. patent application Ser. No. 08/780,224 filed on Jan. 8, 1997 and assigned to Irwin Research and Development, Inc.
The first prior invention of U.S. Pat. No. 4,687,144 was a vast improvement over various types of hammermills that had previously been used. The hammermills were quite bulky, extremely noisy, and prone to substantial damage when the mill received foreign material that it could not comminute. Although such prior Irwin, et al, invention was a vast improvement and was commercially successful, particularly in view of hammermills, it was rather expensive to manufacture and sometimes noisy in operation when processing certain materials. Furthermore, it was unable to satisfactorily comminute rather high density plastic materials.
The improved prior invention of PCT Application No. PCT/U.S. 94/06412 was an improvement over the invention of U.S. Pat. No. 4,687,144. More particularly, an improved comminuting apparatus is taught which is able to produce significantly greater amounts of comminuted material in a given time. Furthermore, such device is less expensive to manufacture and quieter in operation. Even further, the apparatus provides an ability to comminute a wider variety of solid waste products. More particularly, the solid waste comminuting apparatus carries material that is severed in the device via an airstream to a fan. Subdivided pieces of material are directed via the fan to a separator screen which is mounted within a centrifugal housing. The airstream carries small pieces through the separator screen into an outer volute chamber for discharge from the apparatus. Large pieces which are not capable of passing through the separator screen are recycled through a recycle outlet and a recycle conduit back to scissor rolls of the device for further size reduction. However, the complexity of the apparatus and the number of parts needed to construct the apparatus was increased, which has proven undesirable for certain applications.
The improved prior invention of U.S. patent application Ser. No. 08/780,224 was an improvement over the inventions of U.S. Pat. No. 4,687,144 and PCT Application No. PCT/U.S. 94/06412. More particularly, a feed roll delivers solid waste material into overlapping scissor rolls at a desired line speed. A pneumatic conveyor in the form of an Archimedes screw delivers the subdivided pieces of comminuted material for sorting and reprocessing. However, the complexity of the apparatus and the number of parts needed to construct the apparatus was increased.
The object of the present invention is to provide a vastly improved comminuting apparatus that is not only able to process significantly greater amounts of material in a given time, it is better able to recirculate and sort severed solid waste material in the separator screen particularly in an apparatus having a simplified construction with fewer parts, proving more reliable, and is less costly to manufacture, maintain and repair. It is also better able to sever the material at a desired speed, or line speed, in a feed-controlled manner from a web of material being received from a processing machine. Accordingly, the present invention provides an apparatus that is able to feed solid waste material into the comminuting apparatus in a speed-controlled manner.